//! Transport layer abstractions
//! 传输层抽象
//!
//! This module defines the transport layer abstractions for different
//! communication mechanisms.
//!
//! 此模块定义了不同通信机制的传输层抽象。

use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::Duration;

use super::{CommunicationError, CommunicationResult};

/// Transport configuration
/// 传输配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TransportConfig {
    /// Transport type (tcp, unix, grpc, etc.)
    /// 传输类型 (tcp, unix, grpc 等)
    pub transport_type: String,

    /// Connection endpoint
    /// 连接端点
    pub endpoint: String,

    /// Connection timeout
    /// 连接超时
    pub connect_timeout: Duration,

    /// Read timeout
    /// 读取超时
    pub read_timeout: Duration,

    /// Write timeout
    /// 写入超时
    pub write_timeout: Duration,

    /// Keep-alive settings
    /// 保活设置
    pub keep_alive: bool,

    /// Additional transport-specific options
    /// 额外的传输特定选项
    pub options: HashMap<String, String>,
}

impl Default for TransportConfig {
    fn default() -> Self {
        Self {
            transport_type: "unix".to_string(),
            endpoint: "/tmp/spear.sock".to_string(),
            connect_timeout: Duration::from_secs(5),
            read_timeout: Duration::from_secs(30),
            write_timeout: Duration::from_secs(30),
            keep_alive: true,
            options: HashMap::new(),
        }
    }
}

/// Transport statistics
/// 传输统计
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct TransportStats {
    /// Total bytes sent
    /// 总发送字节数
    pub bytes_sent: u64,

    /// Total bytes received
    /// 总接收字节数
    pub bytes_received: u64,

    /// Connection count
    /// 连接数
    pub connection_count: u64,

    /// Reconnection count
    /// 重连次数
    pub reconnection_count: u64,

    /// Last error
    /// 最后错误
    pub last_error: Option<String>,

    /// Transport uptime in seconds
    /// 传输运行时间（秒）
    pub uptime_seconds: u64,
}

/// Transport trait for low-level communication
/// 底层通信的传输 trait
#[async_trait]
pub trait Transport: Send + Sync {
    /// Connect to the transport endpoint
    /// 连接到传输端点
    async fn connect(&self) -> CommunicationResult<()>;

    /// Disconnect from the transport endpoint
    /// 断开传输端点连接
    async fn disconnect(&self) -> CommunicationResult<()>;

    /// Send raw bytes
    /// 发送原始字节
    async fn send_bytes(&self, data: &[u8]) -> CommunicationResult<()>;

    /// Receive raw bytes
    /// 接收原始字节
    async fn receive_bytes(&self) -> CommunicationResult<Vec<u8>>;

    /// Check if transport is connected
    /// 检查传输是否已连接
    async fn is_connected(&self) -> bool;

    /// Get transport statistics
    /// 获取传输统计
    async fn get_stats(&self) -> CommunicationResult<TransportStats>;

    /// Get transport configuration
    /// 获取传输配置
    fn get_config(&self) -> &TransportConfig;
}

/// Unix Domain Socket transport
/// Unix Domain Socket 传输
pub struct UnixTransport {
    config: TransportConfig,
    // TODO: Add actual Unix socket implementation
    // TODO: 添加实际的 Unix socket 实现
}

impl UnixTransport {
    /// Create a new Unix transport
    /// 创建新的 Unix 传输
    pub fn new(config: TransportConfig) -> CommunicationResult<Self> {
        Ok(Self { config })
    }
}

#[async_trait]
impl Transport for UnixTransport {
    async fn connect(&self) -> CommunicationResult<()> {
        // TODO: Implement Unix socket connection
        // TODO: 实现 Unix socket 连接
        Ok(())
    }

    async fn disconnect(&self) -> CommunicationResult<()> {
        // TODO: Implement Unix socket disconnection
        // TODO: 实现 Unix socket 断开连接
        Ok(())
    }

    async fn send_bytes(&self, _data: &[u8]) -> CommunicationResult<()> {
        // TODO: Implement Unix socket send
        // TODO: 实现 Unix socket 发送
        Ok(())
    }

    async fn receive_bytes(&self) -> CommunicationResult<Vec<u8>> {
        // TODO: Implement Unix socket receive
        // TODO: 实现 Unix socket 接收
        Ok(vec![])
    }

    async fn is_connected(&self) -> bool {
        // TODO: Implement connection check
        // TODO: 实现连接检查
        false
    }

    async fn get_stats(&self) -> CommunicationResult<TransportStats> {
        // TODO: Implement stats collection
        // TODO: 实现统计收集
        Ok(TransportStats::default())
    }

    fn get_config(&self) -> &TransportConfig {
        &self.config
    }
}

/// TCP transport
/// TCP 传输
pub struct TcpTransport {
    config: TransportConfig,
    // TODO: Add actual TCP implementation
    // TODO: 添加实际的 TCP 实现
}

impl TcpTransport {
    /// Create a new TCP transport
    /// 创建新的 TCP 传输
    pub fn new(config: TransportConfig) -> CommunicationResult<Self> {
        Ok(Self { config })
    }
}

#[async_trait]
impl Transport for TcpTransport {
    async fn connect(&self) -> CommunicationResult<()> {
        // TODO: Implement TCP connection
        // TODO: 实现 TCP 连接
        Ok(())
    }

    async fn disconnect(&self) -> CommunicationResult<()> {
        // TODO: Implement TCP disconnection
        // TODO: 实现 TCP 断开连接
        Ok(())
    }

    async fn send_bytes(&self, _data: &[u8]) -> CommunicationResult<()> {
        // TODO: Implement TCP send
        // TODO: 实现 TCP 发送
        Ok(())
    }

    async fn receive_bytes(&self) -> CommunicationResult<Vec<u8>> {
        // TODO: Implement TCP receive
        // TODO: 实现 TCP 接收
        Ok(vec![])
    }

    async fn is_connected(&self) -> bool {
        // TODO: Implement connection check
        // TODO: 实现连接检查
        false
    }

    async fn get_stats(&self) -> CommunicationResult<TransportStats> {
        // TODO: Implement stats collection
        // TODO: 实现统计收集
        Ok(TransportStats::default())
    }

    fn get_config(&self) -> &TransportConfig {
        &self.config
    }
}

/// gRPC transport
/// gRPC 传输
pub struct GrpcTransport {
    config: TransportConfig,
    // TODO: Add actual gRPC implementation
    // TODO: 添加实际的 gRPC 实现
}

impl GrpcTransport {
    /// Create a new gRPC transport
    /// 创建新的 gRPC 传输
    pub fn new(config: TransportConfig) -> CommunicationResult<Self> {
        Ok(Self { config })
    }
}

#[async_trait]
impl Transport for GrpcTransport {
    async fn connect(&self) -> CommunicationResult<()> {
        // TODO: Implement gRPC connection
        // TODO: 实现 gRPC 连接
        Ok(())
    }

    async fn disconnect(&self) -> CommunicationResult<()> {
        // TODO: Implement gRPC disconnection
        // TODO: 实现 gRPC 断开连接
        Ok(())
    }

    async fn send_bytes(&self, _data: &[u8]) -> CommunicationResult<()> {
        // TODO: Implement gRPC send
        // TODO: 实现 gRPC 发送
        Ok(())
    }

    async fn receive_bytes(&self) -> CommunicationResult<Vec<u8>> {
        // TODO: Implement gRPC receive
        // TODO: 实现 gRPC 接收
        Ok(vec![])
    }

    async fn is_connected(&self) -> bool {
        // TODO: Implement connection check
        // TODO: 实现连接检查
        false
    }

    async fn get_stats(&self) -> CommunicationResult<TransportStats> {
        // TODO: Implement stats collection
        // TODO: 实现统计收集
        Ok(TransportStats::default())
    }

    fn get_config(&self) -> &TransportConfig {
        &self.config
    }
}

/// Transport factory for creating transport instances
/// 用于创建传输实例的传输工厂
pub struct TransportFactory;

impl TransportFactory {
    /// Create a transport based on configuration
    /// 根据配置创建传输
    pub fn create_transport(config: TransportConfig) -> CommunicationResult<Box<dyn Transport>> {
        match config.transport_type.as_str() {
            "unix" => Ok(Box::new(UnixTransport::new(config)?)),
            "tcp" => Ok(Box::new(TcpTransport::new(config)?)),
            "grpc" => Ok(Box::new(GrpcTransport::new(config)?)),
            _ => Err(CommunicationError::UnsupportedTransport {
                transport_type: config.transport_type,
            }),
        }
    }

    /// Get supported transport types
    /// 获取支持的传输类型
    pub fn supported_transports() -> Vec<&'static str> {
        vec!["unix", "tcp", "grpc"]
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_transport_config_default() {
        let config = TransportConfig::default();
        assert_eq!(config.transport_type, "unix");
        assert_eq!(config.endpoint, "/tmp/spear.sock");
        assert!(config.keep_alive);
    }

    #[test]
    fn test_transport_factory_unix() {
        let config = TransportConfig {
            transport_type: "unix".to_string(),
            ..Default::default()
        };

        let transport = TransportFactory::create_transport(config);
        assert!(transport.is_ok());
    }

    #[test]
    fn test_transport_factory_tcp() {
        let config = TransportConfig {
            transport_type: "tcp".to_string(),
            endpoint: "127.0.0.1:8080".to_string(),
            ..Default::default()
        };

        let transport = TransportFactory::create_transport(config);
        assert!(transport.is_ok());
    }

    #[test]
    fn test_transport_factory_grpc() {
        let config = TransportConfig {
            transport_type: "grpc".to_string(),
            endpoint: "http://127.0.0.1:50051".to_string(),
            ..Default::default()
        };

        let transport = TransportFactory::create_transport(config);
        assert!(transport.is_ok());
    }

    #[test]
    fn test_transport_factory_unsupported() {
        let config = TransportConfig {
            transport_type: "websocket".to_string(),
            ..Default::default()
        };

        let transport = TransportFactory::create_transport(config);
        assert!(transport.is_err());
    }

    #[test]
    fn test_supported_transports() {
        let transports = TransportFactory::supported_transports();
        assert_eq!(transports, vec!["unix", "tcp", "grpc"]);
    }
}
